Optimization of process variables for essential oil components from Satureja hortensis by supercritical fluid extraction using Box-Behnken experimental design

The oil and extracts of Satureja hortensis cultivated in Iran were extracted using supercritical carbon dioxide and hydrodistillation method. The oil and extracts were analyzed by GC-FID and GC/MS. The compounds were identified according to their retention indices and mass spectra (EI, 70 eV). The effects of various parameters such as pressure, temperature, percent of modifier (methanol) and extraction time, were investigated by a fractional factorial design (2^4-1) to determine the significant parameters and their interactions. The results showed that the pressure, temperature and percent of modifier are significant (p < 0.05), but the extraction time was found to be insignificant. The response surface methodology (RSM), based on Box-Behnken design was employed to obtain the optimum conditions of the significant parameters (pressure, temperature and percent of modifier). The optimal conditions could be obtained at a pressure of 35.0 MPa, temperature of 72.6 °C, and 8.6% (v/v) for methanol. The main extracted components using SFE were γ-Terpinene (35.5%), Thymol (18.2%) and Carvacrol (29.7%).